... lL of a substrate solution (Promega, Madison, WI,USA; CytoTox96 assay), and after 15 min of incubation,an additional 50 lL of a stop solution. Thereafter, extinctionwas measured at a wavelength ... up-regulation of PDE1B2 upon mono-cyte-to-macrophage differentiation. Proc Natl Acad SciUSA 102, 497–502.16 Kaneda T, Watanabe A, Shimizu K, Urakawa N &Nakajyo S (2005) Effects of various ... increases intracellular Ca2+in a concentration-dependent waywithout affecting cell viability. Under conditions of enhanced intracellularCa2+concentration, a rapid increase in cAMP levels caused...